This invention relates to a metal pattern forming method capable of forming a ultrathin metal film selectively on an substrate by utilizing a chemical reaction, which may be applied in fabrication of semiconductor device or thin film of conductive material or the like.
Hitherto, the method of preparing a wire pattern in production of semiconductor devices generally involved coating a photosensitive resin film (photoresist) which is decomposed or polymerized by irradiation with light on a substrate having a metal film deposited by evaporation or other method, exposing light in a pattern, developing, forming a resist pattern, and then etching the metal film. In such metal pattern, however, more fine pattern fabrication is being demanded today to increase integration density of the semiconductor devices or the quality of printing.
Especially, for fabrication of VLSI, it is required to produce sub-micron metal patterns with high precision. In such case, although it may greatly depend on the characteristics of the resist resin, it is necessary to coat the resist film as thinly as possible generally to increase resolution, that is, in order to raise the resolution. On the other hand, in the sub-micron pattern fabrication, the wet etching method cannot be applied, and it is necessary to employ dry etching, such as ion etching, plasma etching, and sputter etching, but in order to enhance the resistance of the resist pattern to dry etching, it was generally necessary to fabricate the thick resist film, although the dry etching resistance is dependent on the resist material.
Therefore, to satisfy the above two contradictory requirements, it is desired that any photoresist material be excellent in resolution if the coated film is thick, or excellent in dry etching resistance if the coated film is thin, but such material is thus unknown.